Simplify contract runtime tests

[matklad]

Our average test looks like this:

fn simple_contract() -> Vec
 {
 wat::parse_str(
 r#"
 (module
 (type (;0![](/images/icons/emoticons/wink.png) (func))
 (func (;0![](/images/icons/emoticons/wink.png) (type 0))
 (export "hello" (func 0))
 )"#,
 )
 .unwrap()
 }

#[test]
 fn test_simple_contract() {
 with_vm_variants(|vm_kind: VMKind| 

 { gas_and_error_match( make_simple_contract_call_vm(&simple_contract(), "hello", vm_kind), Some(43032213), None, ); } 

);
 }
 

I find this OK, but I am not entirely satisfied with it. I think we can benefit long-term from spending some cycles on cleaning up this. Specific things I don't like here:

• our WAT is quite dirty, there's no need for (;0![](/images/icons/emoticons/wink.png) comments, we should use $name and (func (export)) shortcuts
• I don't like that we use random hello as an entry point. We should use main, and make it conventional (so that we don't have to specify it)
• explicit with_vm_variants and lambda are a boilerplate we repeat in every test
• gas_and_error_match requires a bit of typing, is prone to chunrn as it depends on the shape of the API (eg, changing errors will lead to a lot of changes), and requires VmError: Eq
• make_simple_contract_call_vm familiy of functions is inconventient when you want to tweak some aspect of the code
• there's a lot of wat::parse-str calls repeated

Ideally, I'd love the tests to be less API-denpendent and more data-driven, and to look like this:

#[test]
 fn test_simple_contract() {
 test_builder()
 .wat(
 r#"
 (module
 (func (export "main")))
 "#,
 )
 .expect(expect![[r#"
 VMOutcome: balance 4 storage_usage 12 return data None burnt gas 42815463 used gas 42815463
 "#]]);
 }

[matklad]

Zulip discussion: https://near.zulipchat.com/#narrow/stream/295306-pagoda.2Fcontract-runtime/topic/Cleaning.20up.20tests

[matklad]

Good point from jakob: with unified infra, we can have a loop over vm_kinds and protocol versions, making sure that old protocol versions preseve behavior.